The damping blocks used in a motor vehicle engine suspension have the task of absorbing the vibrations induced by the pavement in the front zone of the vehicle body and also isolating engine vibrations from the body. The vibrations of the front zone of the body are usually in the range of 15 Hz. In contrast, the vibrations occurring during the operation of the engine have a substantially higher frequency and can be manifested mainly as an acoustic disturbance. It is therefore important to reach a compromise between controlling the vibrations of the front zone of the body and the vibrations occurring during the operation of the engine when selecting the hardness and the damping ability of the damping blocks. Where the damping blocks have rubber webs and these are too hard, the vibrations of the front zone of the body will be almost completely suppressed, but the vibrations occurring during the operation of the engine will be introduced into the body too strongly and lead to a reduction in the acoustic comfort. Not even strong damping in the case of soft rubber webs will completely prevent the transmission of high-frequency vibrations into the body, so that it is not possible to optimize the noise and vibrations into the body by strong damping.
According to German DE-OS No. 35 12, 555, a damping block may be optimized by making an inner portion from two inner bodies which are screwed together by means of a connecting piece. If the inner portion is loaded by the weight of the engine when such a damping block is mounted, it will move downward with its two inner bodies relative to an outer mounting portion. The upper inner body is then screwed upward by means of an adjusting square until it comes into contact with an intermediate layer of rubber in the upper damping block, thus becoming connected to the outer portion via the intermediate layer.
However, it is not possible to achieve load elimination from the upper intermediate rubber layer in the resting state of the engine with the above damping block, because the position in which the upper inner body reaches the rubber layer cannot be fixed in a reliable manner. Contact between the upper inner body and the rubber layer can only be inferred from the increased torque during the screwing upward of the inner body. However, this can also increase considerably for other reasons, e.g., due to tilting of the load to the suspension connection or to irregularities in the threads. Therefore, the desired noise comfort along with a high level of vibration comfort cannot be achieved even with such damping block.